Transactions may include operation or work items that are performed in a distributed fashion by multiple nodes, and may often be implemented on multiple networked computer systems. Transactions arise in a number of different contexts some of which involve evidence of work items involved to complete the transaction. For example, business travel, vacation bookings, itinerary planning, and event reservations may involve a transaction with work items performed by nodes at a number of individual computer systems. For example, booking travel may involve a transaction that requires multiple different parties processing the transaction at different nodes. A travel agent system node may request reservations on various flights, hotels, etc. In response to the requests, one or more airline system nodes may book flight tickets for a traveler. One or more hotel system nodes may create reservations for the traveler, etc.